This invention relates to genetic engineering in yeast.
In the commercial production of proteins via recombinant DNA technologies, it is often advantageous for the desired protein to be secreted into the growth medium, in order to facilitate the recovery of the desired protein. Secretion of proteins from cells is generally accomplished by the presence of a short stretch of hydrophobic amino acids constituting the amino-terminal end of the primary translation product. This hydrophobic stretch is called the "secretory signal sequence", and it is possible to use such signal sequences to effect the secretion of heterologous proteins. This is generally accomplished by the construction of an expression vector comprising a DNA sequence encoding a secretory signal sequence, into which a gene encoding the desired heterologous protein is inserted. When such a plasmid is transformed into a host cell, the host cell will express the desired protein product and secrete the protein into the growth medium. Such secretion vectors have been constructed for a variety of microorganisms, including E. coli (Gilbert et al., U.S. Pat. No. 4,338,397) B. subtilis, S. lividans and S. cerevisiae.
Because of the considerable amount that is known about the genetics and molecular biology of S. cerevisiae, yeast is a desirable organism to use for secretion systems. Kurjan et al. (U.S. Pat. No. 4,546,082) discloses a yeast secretion vector based on the signal sequence from the alpha-factor gene.